Ellipse compass



Sept. 24, 1963 Filed Nov. 23, 1962 C. W. KING ELLIPSE COMPASS 2 Sheets-Sheet l INVENTOR.

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ELLIPSE COMPASS Filed Nov. 25, 1962 2 Sheets-Sheet 2 y INVENTOR @Ji CHA/@.455 /6/1/6 3,104,466 ELLIPSE COMPASS Charles W. King, 5609 Larkspur Lane, North Littie Rock, Ark. Filed Nov. 23, 1962, Ser. No. 239,679 3 Claims. (Cl. 33 27) This invention relates to drating instruments, and more particularly to a compass for drawing a non-circular figure such as an ellipse or oval.

A main object of the invention is to provide a novel and improved instrument for use .in drawing a closed, non-circular ligure, such as an oval or an ellipse, the instrument 'being relatively simple in construction, being easy to use, and being adjustable so that the ellipse angle can be readily selected.

A further object of the invention is to provide an improved ellipse compass which is relatively inexpensive to manufacture, which is durable in construction, which is relatively compact in size, and which is calibrated so that the user can readily select the desired ellipse angle corresponding to the ellipse to 'be inscribed by the instrument.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIGURE l is a vertical longitudinal cross sectional view taken through an improved ellipse compass constructed in accordance with the present invention.

FIGURE 2 is a horizontal cross sectional view taken substantially on the line 2 2 of FIGURE 1.

FIGURE 3 is a fragmentary enlarged cross sectional View taken substantially on the line 3 3- of FIGURE 1.

FIGURE 4 is a horizontal cross sectional view taken on the line 4 4 of FIGURE l.

FIGURE 5 is a perspective view of the plunger employed inthe hollow horizontal arm of the ellipse compass shown in FIGURE l. Y

FIGURE 6 is a vertical longitudinal cross sectional view of the ellipse compass, similar to FIGURE 1, but showing the sleeve member in a position rotated 90 with respect to the main leg of the instrument, -as compared with FIG- URE 1.

FIGURE 7 is an enlarged horizontal cross sectional view taken substantially on the line 7 7 of FIGURE 6.

FIGURE 8 is an enlarged horizontal cross sectional View taken substantially on the line 8 8 of FIGURE 6.

FIGURE 9 is an enlarged fragmentary side elevational view taken substantially on the line 9 9' of FIGURE l.

Referring to the drawings, 11 generally designates an improved drafting instrument constructed in accordance with the present invention. The instrument 11 comprises a rst leg 12 which is provided with the tapered bottom end 13 which terminates in a point '14. Slidably engaged in the leg 12 and extending longitudinally therethrough closely adjacent to the axis of the leg 12 is an elongated anchoring pin 1S having a pointed bottom end 16 an-d provided at its top end with an enlarged button or head 17 adapted to be pressed downwardly to cause the point 16 to engage in the paper on which an ellipse is to be inscribed, as will be presently explained. A biasing spring 18, comprising a coiled spring, surrounds the upper portion of the pin 15, bearing between the head 17 and the top end of the reduced upper portion 19 of leg 12. The coiled spring 1S biases the pin 15 upwardly to a retracted position. 'Ihe point 16 may be moved downwardly into engagement with the drawing paper by pressing downwardly on the head 17 against the `force of the biasing spring 18.

The reduced upper portion 19 of the leg 12- is of generally rectangular cross sectional sh-ape and extends through the rectangular bore of a guide member 20. The member 2i) is formed with the axial rectangular bore 21 which tightly receives the reduced portion 19 and which is substantially frictionally secured thereto so that it is -xed ou portion 19.

The guide member 20* is formed withvthe externally threaded top portion 22 which is threadedly engaged by a top cap member 23, said cap member having the internal threads 2.4 adapted to threadedly engage on the external threads of the member 22, as shown in FIGURE l.

The top clap 23 is provided with the enlarged top flange 25 which is formed with a radial tapped bore 26 in which is threadedly engaged a set screw 27 which can be tightened to clampingly engage the top portion of element 19, whereby .to rigidly secure the cap 23 to said element 19,

The bottom end of the cap 23 is formed with the circular recess 26 receiving the top end of a sleeve member 27 rotatably mounted on the leg 12, Said sleeve member being formed at its top end with an annular recess 28 which receives the inner end portions of a plurality of retaining pins 29 secured to and projecting inwardly lfrom the skirt-like bottom rim portion of the member 23. This rotatably connects the cap 23 to the sleeve member 27, allowing the leg 12 to be held stationary while the sleeve 27 is rotated therearound in a manner presently to be described.

The lower portion of the guide member 20* is downwardly tapered, as shown at 30, and the tapered portion 30 is of generally oval cross section, with the minor diameter thereof diminishing in a downward direction, as will be clearly apparent from FIGURES 2 and 4. Thus, the member 20 is of generally elliptical horizontal cross section with a substantially constant major diameter, equal substantially to the internal `diameter of the sleeve 27, but Y with a minor diameter which decreases in a downward direction.

The sleeve member 27 is integrally formed with an outwardly extending, substantially horizontal hollow arm 31 in which is slidably mounted a plunger 32, said plunger having the tapered inwardly directed tip 33 which is biased into engagement with the lower portion 30 of member 20! lby a coiled spring 34 disposed between the outer en-d of plunger 32 and the end cap 3S threadedly secured on arm 31.`

The plunger 32 is formed with the perpendicularly intersecting longitudinally extending slots 36 and 37, the slot 36 extending through the entire width of the plunger and the slot 3-7 extending sufficiently into the plunger' to intersect the slot 36, as shown in FIGURE 2.

Designated generally at 38 is a secondleg which has the longitudinally slotted shank portion 39 which extends slidably through vertically aligned top and bottom slots 40, 40 of arm 31 and through the longitudinal slot 36 of plunger 32. Extending through a longitudinal horizontal slot 42 provided in aum 31 is a clamping screw 43, which extends transversely through the plunger slot 37 and through the longitudinal slot 44 of leg element 39 and is threadedly engaged with a nut 45 provided in the recess 37 adjacent the inside `surface of the upper leg portion 39.

The leg 38 is provided with the pivoted lower portion 47 having a scribingrpoint, such as a pencil point, or the like, shown at 48, at its bottom end.

It will be noted that the ysleeve 27 and its arm 31 may be adjusted vertically relative to the leg 12 by rotating the cap 23 relative to leg 12, whereby to advance or retract cap 23 with respect to the threaded portion 22. This varies the point of engagement of the plunger tip 33 on vthe tapered |guide portion 30, so that the tip 33 engages cross sectional areas of member 30` having difyferent minor diameters. Said different minor diam-eters correspond -to ellipses of different angles, namely, ellipses corresponding to circular projections at said dilerent angles. The sleeve member 27 is provided with a vertical window or slot 50 located adjacent the top edge of the tapered portion 30, and is lfurther provided on opposite sides of said slot 50` with an angle scale 5l calibrated to indicate the ellipse angle of the cross section of the portion of member 3d engaged by the tip 33. rl`hus, the top edge of lmember 30, shown at 52 in FIGURE 9, moves along the scale 51 as the cap 23 is rotated relative to leg 12, thus indicating the ellipse angle of the portion of the cross section of member 30 engaged by tip 33. This enables the instrument to be adjusted to draw an ellipse or oval of a desired angle.

The size, namely, the major diameter of the ellipse or oval to be inscribed may be adjusted by adjusting the position of the slotted upper portion 39 of leg 318 along the arm 31. The clamping screw 43 is provided with an integral collar portion S4 lwhich is slidable in the slot 42 but which is enlarged with respect to the shank portion 55 of screw 43, as shown in FIGURE 2, so that the collar portion 54 will clampingly engage against the plunger 32 when the screw 43 `is tightened. Thus, the slotted portion 39 of leg 38 may be locked in any desired angular position or any desired position of adjustment along the arm 31 by tightening the clamping screw `43.

ln using the instrument, the pin member 1S is iirst depressed, as shown in FIGURE v6, so that the point d4 engages on the @desired centerpoint of the ellipse or oval to be drawn. With the head 17 depressed and with the operators hand grasping the cap 23, the arm 3l, is then rotated along with the sleeve 27 around the leg Y12, which is held stationary, so that the scribing point 48 inscribes a closed gure on the paper, responsive to a complete revolution of arm 31 and sleeve 27, whose shape corresponds to the shape of the cross section of member 30 engaged by the tip 33. The closed ligure inscribed by a complete revolution of sleeve 27 and arn'i 31 around leg 12 will be of generally oval form and will resemble an ellipse of an angle in laccordance with the angular indication |corresponding to the position of edge 52 along scale 51. The described figure can be made to approximate a true ellipse by suitably forming the guide surface of the tapered portion Sil so that the variations in radius of the cross section engaged by the tip 33 will produce suicient variations in radius of point 48 with respect to point 16 as the sleeve 27 and arm 31 are rotated around leg 12 to produce the desired ellipse.

The sleeve 27 is provided at its lower port-ion with a set screw 60 which is normally adjusted -to a retracted position so that it does not interfere with the rotation of sleeve 27 with respect to the leg 12. However, the set screw 6G may be screwed inwardly to clampingly engage with the leg 12 so that the sleeve 2:7 is locked to said leg, enabling the instrument to be employed to draw circles, as in the case of a conventional compass.

The `clamping screw |69 is retained by the provision of an inwardly projecting pin 63 Vprovided in the internally threaded integral bore 64 on sleeve 27 carrying the screw 60, the pin 63 engaging in an annular groove 65 lformed in the shank of screw y6i), said groove 65 being of substantial longitudinal length so as to enable the screw 60 to be loosened or tightened, the pin 63 engaging in Y the lgroove 65 to prevent loss of the screw 60 when said screw is in its loosened posi-tion. v

The exposed portion of the member 31B viewed through the slot 50 may be provided with any suitable index element or marking to serve as a pointer with reference to the scale 51, or alternatively, the top edge of the portion 30 may be employed as such a marker or index means.

While a speciiic embodiment of an improved ellipse compass has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, itis intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. =An instrument for 4drawing ovals comprising a first leg with a point, said lirst leg having an intermediate oval-Y forming guide portion, said guide portion varying vertically in cross-sectional shape, a sleeve member slidably receiving and rotatably mounted on said first leg and having an outwardly extending hollow arm, an adjusting head rotatably connected to said sleeve member and threadedly engaged with said iirst leg, -whereby to adjust said sleeve member axially on said first leg responsive to rotation of said head, a plunger slidably mounted in said arm, means biasing said plunger into engagement with said oval-forming guide portion, a second leg secured to and depending from the intermediate portion of said plunger,

in said arm, means biasing said plunger into engagement with said oval-forming guide portion, a longitudinally slotted second leg, said second leg being provided with a scribing point on its bottom end, said hollow arm and plunger being formed ywith registering slots receiving said second leg, and clamping means extending transversely into the hollow arm and plunger and through thev slot Vin said second leg and adjustably `clamping said second leg to the plunger.

3. An instrument for drawing ovals comprising a iirst leg provided with a pointed anchor-ing pin extending slidably and longitudinally therethrough, said first legy hav- 'i ing an intermediate oval-forming guide portion, said guide portion varying vertically in cross-section shape, a sleeve member rotatably mounted on said lirst leg and having an outwardly extending hollow arm, an adjusting head rotatably connected to said sleeve member and threadedly engaged with said first leg, whereby to adjust said sleeve member axially on said irst leg responsive t0 rotation of said head, a plunger slidably mounted in said arm, means biasing said plunger into engagement with said oval-forming vguide portion, a longitudinally slotted second leg, said second leg provided with a scribing point on its bot-tom end, said` hollow arm and plunger being formed with registering slots receiving said secondV leg, and clamping -means extending transversely into the hollow arm and plunger and through the slot in said secr ond leg and adjustably clamping said secondy leg tothe plunger.

References Cited in the file of this patent UNITED STATES PATENTS Austria Dec. l0; 1924 

1. AN INSTRUMENT FOR DRAWING OVALS COMPRISING A FIRST LEG WITH A POINT, SAID FIRST LEG HAVING AN INTERMEDIATE OVALFORMING GUIDE PORTION, SAID GUIDE PORTION VARYING VERTICALLY IN CROSS-SECTIONAL SHAPE, A SLEEVE MEMBER SLIDABLY RECEIVING AND ROTATABLY MOUNTED ON SAID FIRST LEG AND HAVING AN OUTWARDLY EXTENDING HOLLOW ARM, AN ADJUSTING HEAD ROTATABLY CONNECTED TO SAID SLEEVE MEMBER AND THREADEDLY ENGAGED WITH SAID FIRST LEG, WHEREBY TO ADJUST SAID SLEEVE MEMBER AXIALLY ON SAID FIRST LEG RESPONSIVE TO ROTATION OF SAID HEAD, A PLUNGER SLIDABLY MOUNTED IN SAID ARM, MEANS BIASING SAID PLUNGER INTO ENGAGEMENT WITH SAID OVAL-FORMING GUIDE PORTION, A SECOND LEG SECURED TO AND 